Biology subjects

Dai, Z.

Publications and source records attributed to Dai, Z..

At least 73 records · Page 4Linked to original sources

bioRxiv2023

Proximity Labeling Expansion Microscopy (PL-ExM) resolves structure of the interactome

Elucidating the spatial relationships within the protein interactome is pivotal to understanding the organization and regulation of protein-protein interactions. However, capturing the 3D architecture of the interactome presents a dual challenge: precise interactome labeling and super-resolution imaging. To bridge this gap, we present the Proximity Labeling Expansion Microscopy (PL-ExM). This innovation combines proximity labeling (PL) to spatially biotinylate interacting proteins with expansion microscopy (ExM) to increase imaging resolution by physically enlarging cells. PL-ExM unveils intricate details of the 3D interactomes spatial layout in cells using standard microscopes, including confocal and Airyscan. Multiplexing PL-ExM imaging was achieved by pairing the PL with immunofluorescence staining. These multicolor images directly visualize how interactome structures position specific proteins in the protein-protein interaction network. Furthermore, PL-ExM stands out as an assessment method to gauge the labeling radius and efficiency of different PL techniques. The accuracy of PL-ExM is validated by our proteomic results from PL mass spectrometry. Thus, PL-ExM is an accessible solution for 3D mapping of the interactome structure and an accurate tool to access PL quality.

bioengineering↗

bioRxiv2023

A conserved N-terminal motif of CUL3 mediates assembly and licenses E3 ligase activation of CRL3KLHL22

The CUL3-RING E3 ubiquitin ligases (CRL3s) play an essential role in response to extracellular nutrition and stress stimuli. The ubiquitin ligase function of CRL3s is activated through E3-E3 dimerization. However, how and why such a dimeric assembly is required for its ligase activity remains elusive. Here, we report the cryo-EM structure of the dimeric CRL3KLHL22 complex and reveal a conserved N-terminal motif in CUL3 that mediates the dimerization assembly and licenses the activation of CRL3KLHL22. Deletion of the CUL3 N-terminal motif leads to non-stochiometric assembly and impairs E3 activity of both CRL3KLHL22 and several other CRL3s. In addition, we found that the dynamics of dimeric E3-E3 superassembly generates a variable ubiquitination zone, potentially facilitating substrate recognition and ubiquitination. These findings demonstrate a CUL3 N-terminal motif-dependent E3-E3 superassembly mechanism and provide insights into the assembly and activation of CRL3s.

molecular biology↗

bioRxiv2023

SARS-CoV-2 N protein-induced Dicer, XPO5, SRSF3, and hnRNPA3 downregulation causes pneumonia

Age is a major risk factor for coronavirus disease (COVID-19)-associated severe pneumonia and mortality; however, the underlying mechanism remains unclear. Herein, we investigated whether age-related deregulation of RNAi components and RNA splicing factors affects COVID-19 severity. Decreased expression of RNAi components (Dicer and XPO5) and splicing factors (SRSF3 and hnRNPA3) correlated with increased severity of COVID-19 and SARS-CoV-2 nucleocapsid (N) protein-induced pneumonia. N protein induced autophagic degradation of Dicer, XPO5, SRSF3, and hnRNPA3, repressing miRNA biogenesis and RNA splicing and inducing DNA damage, proteotoxic stress, and pneumonia. Dicer, XPO5, SRSF3, and hnRNPA3 were downregulated with age in mouse lung tissues. Older mice experienced more severe N protein-induced pneumonia than younger mice. However, treatment with a poly(ADP-ribose) polymerase inhibitor (PJ34) or aromatase inhibitor (anastrozole) relieved N protein-induced pneumonia by restoring Dicer, XPO5, SRSF3, and hnRNPA3 expression. These findings will aid in developing improved treatments for SARS-CoV-2-associated pneumonia.

microbiology↗

bioRxiv2023

A redundant chloroplast protein is co-opted by potyvirids as the scaffold protein to mediate viral intercellular movement complex assembly

For viruses in the family Potyviridae (potyvirids), three virus-encoded proteins (P3N-PIPO, CI and CP) and several host components are known to coordinately regulate viral cell-to-cell movement. Here, we found that HCPro2 encoded by areca palm necrotic ring spot virus is involved in the intercellular movement, which could be functionally complemented by its counterpart HCPro from a potyvirus. The affinity purification and mass spectrum analysis identified several viral factors (including CI and CP) and a variety of host proteins that physically associate with HCPro2. We demonstrated that HCPro2 interacts with either CI or CP in planta, and the three form plasmodesmata (PD)-localized interactive complex in viral infection. Further, we screened HCPro2-associating host proteins, and identified a common host protein RbCS that mediates the interactions of HCPro2-CI, HCPro2-CP and CI-CP among the complex. Knockdown of NbRbCS simultaneously impairs the interactions of HCPro2-CI, HCPro2-CP and CI-CP, and significantly attenuates the intercellular movement and systemic infection for ANRSV and other three tested potyvirids. This study highlights that a nucleus-encoded chloroplast-targeted protein is hijacked by potyvirids as the scaffold protein to mediate the assembly of viral intercellular movement complex to promote viral infection.

microbiology↗

bioRxiv2023

Physiologic Doses of TGF-beta Improve the Composition of Engineered Articular Cartilage

For cartilage regeneration applications, transforming growth factor beta (TGF-{beta}) is conventionally administered at highly supraphysiologic doses (10-10,000 ng/mL) in an attempt to cue cells to fabricate neocartilage that matches the composition, structure, and functional properties of native hyaline cartilage. While supraphysiologic doses enhance ECM biosynthesis, they are also associated with inducing detrimental tissue features, such as fibrocartilage matrix deposition, pathologic-like chondrocyte clustering, and tissue swelling. Here we investigate the hypothesis that moderated TGF-{beta} doses (0.1-1 ng/mL), akin to those present during physiological cartilage development, can improve neocartilage composition. Variable doses of media-supplemented TGF-{beta} were administered to a model system of reduced-size cylindrical constructs (O2-O3 mm), which mitigate the TGF-{beta} spatial gradients observed in conventional-size constructs (O4-O6 mm), allowing for a novel assessment of the intrinsic effect of TGF-{beta} doses on macroscale neocartilage properties and composition. The administration of physiologic TGF-{beta} to reduced-size constructs yields neocartilage with native-matched sGAG content and mechanical properties while providing a more hyaline cartilage-like composition, marked by: 1) reduced fibrocartilage-associated type I collagen, 2) 77% reduction in the fraction of cells present in a clustered morphology, and 3) 45% reduction in the degree of tissue swelling. Physiologic TGF-{beta} appears to achieve an important balance of promoting requisite ECM biosynthesis, while mitigating hyaline cartilage compositional deficits. These results can guide the development of novel physiologic TGF-{beta}-delivering scaffolds to improve the regeneration clinical-sized neocartilage tissues.

bioengineering↗

bioRxiv2023

Functional connectome through the human life span

The lifespan growth of the functional connectome remains unknown. Here, we assemble task-free functional and structural magnetic resonance imaging data from 33,250 individuals aged 32 postmenstrual weeks to 80 years from 132 global sites. We report critical inflection points in the nonlinear growth curves of the global mean and variance of the connectome, peaking in the late fourth and late third decades of life, respectively. After constructing a fine-grained, lifespan-wide suite of system-level brain atlases, we show distinct maturation timelines for functional segregation within different systems. Lifespan growth of regional connectivity is organized along a primary-to-association cortical axis. These connectome-based normative models reveal substantial individual heterogeneities in functional brain networks in patients with autism spectrum disorder, major depressive disorder, and Alzheimers disease. These findings elucidate the lifespan evolution of the functional connectome and can serve as a normative reference for quantifying individual variation in development, aging, and neuropsychiatric disorders.

neuroscience↗

bioRxiv2023

The Unexpected Role of GCN2 Kinase Activation in Mediating Pulmonary Vascular Remodeling and Pulmonary Arterial Hypertension

BackgroundPulmonary arterial hypertension (PAH) is characterized by progressive increase of pulmonary vascular resistance and remodeling that result in right heart hypertrophy and failure. Published studies show that recessive mutations of EIF2AK4 gene (encoding GCN2, General control nonderepressibe 2 kinase) are linked to heritable pulmonary veno-occlusive disease (PVOD) in patients and EIF2AK4 mutations were also found in PAH patients although very rare. However, the role of GCN2 kinase in the pathogenesis of PAH remains unclear. MethodsEif2ak4-/- mice with genetic disruption of the kinase domain and GCN2 kinase inhibitor A-92 were employed in animal models of PH including chronic hypoxia-exposed mice and monocrotaline-challenged rats. Human lung endothelial cells (HLMVECs) were used for mechanistic studies. Endothelium-targeted nanoparticles were employed to deliver plasmid DNA to adult mice to knockout Eif2ak4 or overexpress Endothelin-1 (Edn1) selectively in ECs. ResultsHere we show that loss of GCN2 induced neither spontaneous PVOD nor PH in Eif2ak4-/- mice but inhibited hypoxia-induced PH evident by reduced right ventricular systolic pressure, right ventricle hypertrophy and pulmonary vascular remodeling. RNA sequencing analysis suggested Edn1 as the downstream target of GCN2. In cultured HLMVECs, GCN2 was phosphorylated and activated in response to hypoxia, mediating hypoxia-induced Edn1 expression via HIF-2. Restored Edn1 expression in ECs in Gcn2-deficient mice reversed the reduced phenotype of hypoxia-induced PH. Furthermore, loss of endothelial Eif2ak4 in mice attenuated hypoxia-induced PH. Monocrotaline-induced PH and pulmonary vascular remodeling in rats were inhibited by GCN2 inhibitor A-92 treatment. The clinical relevance of the observation was validated by GCN2 hyperphosphorylation indicative of activation in ECs of pulmonary vascular lesions of PAH patients. ConclusionThese studies demonstrate that GCN2 activation by hypoxia mediates pulmonary vascular remodeling and PAH through Edn1. Thus, targeting GCN2 signaling is a promising therapeutic strategy for treatment of PAH in patients without EIF2AK4 loss of function mutations.

physiology↗

bioRxiv2023

De novo progesterone synthesis in plants

The essential roles of progesterone and other C21 steroids in animals are well-documented. Progesterone is an essential hormone for females to maintain a regular menstrual cycle and pregnancy, while also exhibiting anti-inflammatory and antitumor effects. While the biosynthesis pathway of C21 steroids is comprehensively understood in animals, the synthesis mechanisms of progesterone in plants remain unclear. To our best knowledge, this is the first study to elucidate the complete pathway for progesterone biosynthesis in the plant Marsdenia tenacissima, involving the two sterol side chain cleaving cytochrome P450 enzymes (P450scc) Mt108 or Mt150, as well as the {Delta}5-3{beta}-hydroxysteroid dehydrogenase/{Delta}5-{Delta}4 ketosteroid isomerase MtHSD5. This critical discovery paves the way for the sustainable synthesis of steroid hormone drugs using either plants or microbial host cells.

plant biology↗

bioRxiv2023

Comammox bacterial preference for urea influences its interactions with aerobic nitrifiers.

While the co-existence of comammox bacteria with canonical nitrifiers is well documented in diverse ecosystems, there is still a dearth of knowledge about the mechanisms underpinning their interactions. Understanding these interaction mechanisms is important as they may play a critical role in governing nitrogen biotransformation in natural and engineered ecosystems. In this study, we tested the ability of two environmentally relevant factors (nitrogen source and availability) to shape interactions between strict ammonia and nitrite-oxidizing bacteria and comammox bacteria in continuous flow column reactors. The composition of inorganic nitrogen species in reactors fed either ammonia or urea was similar during the lowest nitrogen loading condition (1 mg-N/L), but higher loadings (2 and 4 mg-N/L) promoted significant differences in nitrogen species composition and nitrifier abundances. The abundance and diversity of comammox bacteria were dependent on both nitrogen source and loading conditions as multiple comammox bacterial populations were preferentially enriched in the urea-fed system. In contrast, their abundance was reduced in response to higher nitrogen loadings in the ammonia-fed system likely due to ammonia-based inhibition. The preferential enrichment of comammox bacteria in the urea-fed system could be associated with their ureolytic activity calibrated to their ammonia oxidation rates thus minimizing ammonia accumulation to inhibitory levels. However, an increased abundance of comammox bacteria was not associated with a reduced abundance of nitrite oxidizers in the urea-fed system while a negative correlation was found between them in the ammonia-fed system; the latter dynamic likely emerging from reduced availability of nitrite to strict nitrite oxidizers at low ammonia loading conditions. ImportanceNitrification is an essential biological process in drinking water and wastewater treatment systems for managing nitrogen and protecting downstream water quality. The discovery of comammox bacteria and their detection alongside canonical nitrifiers in these engineered ecosystems has made it necessary to understand the environmental conditions that regulate their abundance and activity relative to other better-studied nitrifiers. This study aimed to evaluate two important factors that could potentially influence the behavior of nitrifying bacteria, and therefore impact nitrification processes. Colum reactors fed with either ammonia or urea were systematically monitored to capture changes in nitrogen biotransformation and the nitrifying community as a function of influent nitrogen concentration, nitrogen source, and reactor depth. Our findings show that comammox bacterial abundance decreased and that of nitrite oxidizers increased with increased ammonia availability, while their abundance and diversity increased with increasing urea availability without driving a reduction in the abundance of canonical nitrifiers.

microbiology↗

bioRxiv2023

Cotyledon Peeling Method for Passion Fruit Protoplasts: a versatile cell system for transient gene expression in passion fruit (Passiflora edulis)

Passion fruit (Passiflora edulis) is a perennial evergreen vine that grows mainly in tropical and subtropical regions due to its nutritional, medicinal and ornamental values. However, the molecular biology study of passion fruit is extremely hindered by the lack of an easy and efficient method for transformation. The protoplast transformation system plays a vital role in plant regeneration, gene function analysis and genome editing. Here, we present a new method ( Cotyledon Peeling Method) for simple and efficient passion fruit protoplast isolation using cotyledon as the source tissue. A high yield (2.3 x 107 protoplasts per gram of fresh tissues) and viability (76%) of protoplasts were obtained upon incubation in the enzyme solution [1% (w/v) cellulase R10, 0.25% (w/v) macerozyme R10, 0.4 M mannitol, 10 mM CaCl2, 20 mM KCl, 20 mM MES and 0.1% (w/v) BSA, pH 5.7] for 2 hours. In addition, we achieved high transfection efficiency of 83% via the polyethylene glycol (PEG)-mediated transformation with a green fluorescent protein (GFP)-tagged plasmid upon optimization. The crucial factors affecting transformation efficiency were optimized as follows: 3 g of plasmid DNA, 5 min transfection time, PEG concentration at 40% and protoplast density of 100 x 104 cells/ml. Furthermore, the established protoplast system was successfully applied for subcellular localization analysis of multiple fluorescent organelle markers and protein-protein interaction study. Taken together, we report a simple and efficient passion fruit protoplast isolation and transformation system, and demonstrate its usage in transient gene expression for the first time in passion fruit. The protoplast system would provide essential support for various passion fruit biology studies, including genome editing, gene function analysis and whole plant regeneration.

plant biology↗

bioRxiv2023

YAP/TAZ enhance P-body formation to promote tumorigenesis

The role of Processing bodies (P-bodies) in tumorigenesis and tumor progression is not well understood. Here, we showed that the oncogenes YAP/TAZ promote P-body formation in a series of cancer cell lines. Mechanistically, both transcriptional activation of the P- body-related genes SAMD4A, AJUBA, and WTIP and transcriptional suppression of the tumor suppressor gene PNRC1 are involved in enhancing the effects of YAP/TAZ on P- body formation in CRC cells. By reexpression of PNRC1 or knockdown of P-body core genes (DDX6, DCP1A, and LSM14A), we determined that disruption of P-bodies attenuates cell proliferation, cell migration and tumor growth induced by overexpression of YAP5SA in CRC. Analysis of a pancancer CRISPR screen database (DepMap) revealed codependencies between YAP/TEAD and the P-body core genes and correlations between the mRNA levels of SAMD4A, AJUBA, WTIP, PNRC1 and YAP target genes. Our study suggests that the P-body is a new downstream effector of YAP/TAZ, which implies that reexpression of PNRC1 or disruption of P-bodies is a potential therapeutic strategy for tumors with active YAP.

cell biology↗

bioRxiv2023

HMGB1 acts as an agent of host defense at the gut mucosal barrier

Mucosal barriers provide the first line of defense between internal body surfaces and microbial threats from the outside world.1 In the colon, the barrier consists of two layers of mucus and a single layer of tightly interconnected epithelial cells supported by connective tissue and immune cells.2 Microbes colonize the loose, outer layer of colonic mucus, but are essentially excluded from the tight, epithelial-associated layer by host defenses.3 The amount and composition of the mucus is calibrated based on microbial signals and loss of even a single component of this mixture can destabilize microbial biogeography and increase the risk of disease.4-7 However, the specific components of mucus, their molecular microbial targets, and how they work to contain the gut microbiota are still largely unknown. Here we show that high mobility group box 1 (HMGB1), the prototypical damage-associated molecular pattern molecule (DAMP), acts as an agent of host mucosal defense in the colon. HMGB1 in colonic mucus targets an evolutionarily conserved amino acid sequence found in bacterial adhesins, including the well-characterized Enterobacteriaceae adhesin FimH. HMGB1 aggregates bacteria and blocks adhesin-carbohydrate interactions, inhibiting invasion through colonic mucus and adhesion to host cells. Exposure to HMGB1 also suppresses bacterial expression of FimH. In ulcerative colitis, HMGB1 mucosal defense is compromised, leading to tissue-adherent bacteria expressing FimH. Our results demonstrate a new, physiologic role for extracellular HMGB1 that refines its functions as a DAMP to include direct, virulence limiting effects on bacteria. The amino acid sequence targeted by HMGB1 appears to be broadly utilized by bacterial adhesins, critical for virulence, and differentially expressed by bacteria in commensal versus pathogenic states. These characteristics suggest that this amino acid sequence is a novel microbial virulence determinant and could be used to develop new approaches to diagnosis and treatment of bacterial disease that precisely identify and target virulent microbes.

microbiology↗

bioRxiv2023

E2F1 Mediates SOX17 Deficiency-Induced Pulmonary Hypertension

RationaleRare genetic variants and genetic variation at loci in an enhancer in SRY-Box Transcription Factor 17 (SOX17) are identified in patients with idiopathic pulmonary arterial hypertension (PAH) and PAH with congenital heart disease. However, the exact role of genetic variants or mutation in SOX17 in PAH pathogenesis has not been reported. ObjectivesTo investigate the role of SOX17 deficiency in pulmonary hypertension (PH) development. MethodsHuman lung tissue and endothelial cells (ECs) from IPAH patients were used to determine the expression of SOX17. Tie2Cre-mediated and EC-specific deletion of Sox17 mice were assessed for PH development. Single-cell RNA sequencing analysis, human lung ECs, and smooth muscle cell culture were performed to determine the role and mechanisms of SOX17 deficiency. A pharmacological approach was used in Sox17 deficiency mice for therapeutic implication. Measurement and Main ResultsSOX17 expression was downregulated in the lungs and pulmonary ECs of IPAH patients. Mice with Tie2Cre mediated Sox17 knockdown and EC-specific Sox17 deletion developed spontaneously mild PH. Loss of endothelial Sox17 in EC exacerbated hypoxia-induced PH in mice. Loss of SOX17 in lung ECs induced endothelial dysfunctions including upregulation of cell cycle programming, proliferative and anti-apoptotic phenotypes, augmentation of paracrine effect on pulmonary arterial smooth muscle cells, impaired cellular junction, and BMP signaling. E2F Transcription Factor 1 (E2F1) signaling was shown to mediate the SOX17 deficiency-induced EC dysfunction and PH development. ConclusionsOur study demonstrated that endothelial SOX17 deficiency induces PH through E2F1 and targeting E2F1 signaling represents a promising approach in PAH patients.

physiology↗

bioRxiv2023

Ferroptosis is determined by chloride ions

Ferroptosis has emerged as a deliberate type of programmed cell death that manifests marked importance ubiquitously in health and diseases. However, after a decade of research, the mechanisms of ferroptosis execution remain unclear. Here we identify chloride ions (Cl-) as essential determinants of ferroptosis. Water homeostasis manipulated by extracellular solute concentration disrupts ferroptotic cell death. Hyperosmotic stress attenuates ferroptosis and endues cells with high lipid peroxidation. Analyses of a fluorescent chloride probe show that Cl- fluxes into the cytoplasm during ferroptosis, substantiating a role for Cl- to drive water flow. Depletion of extracellular chloride ions ([Cl-]o) from culture media congruously confers resistance to ferroptosis. The [Cl-]o-depleted ferroptotic cells fall into two populations: cells with low lipid peroxidation; cells with high lipid peroxidation but not cell swelling or cell rupture. Contrarily, solitary [Cl-]o overload is sufficient to elicit ferroptosis without canonical ferroptosis inducers. Further experiments show that ferroptotic cells depolarize and [Cl-]o is positively correlated with this process. Membrane depolarization upregulates the level of lipid peroxidation, suggesting that membrane potential may be a universal mechanism governing ferroptosis. Together, our findings reveal that ferroptosis is determined by chloride ions.

cell biology↗

bioRxiv2023

USP39 promotes hepatocellular carcinogenesis through regulating alternative splicing in cooperation with SRSF6/HNRNPC

Abnormal alternative splicing (AS) caused by alterations in spliceosomal factors is implicated in cancers. Standard models posit that splice site selection is mainly determined by early spliceosomal U1, U2 snRNPs. Whether and how other mid/late-acting spliceosome components such as USP39 modulate tumorigenic splice site choice remain largely elusive. We observed that hepatocyte-specific knock-in of USP39 promoted hepatocarcinogenesis and potently regulated splice site selection. In human liver cancer cells, USP39 promoted tumor proliferation in a spliceosome-dependent manner. USP39 depletion deregulated hundreds of AS events, including the oncogenic splice-switching of KANK2. Mechanistically, we developed a novel RBP-motif enrichment analysis and found that USP39 modulated exon inclusion/exclusion by interacting with SRSF6/HNRNPC in both humans and mice. Our data represent a paradigm for the control of splice site selection by mid/late-acting spliceosome proteins and their interacting RBPs. USP39 and possibly other mid/late-acting spliceosome proteins may represent potential prognostic biomarkers and targets for cancer therapy. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=97 SRC="FIGDIR/small/525324v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@34cbc1org.highwire.dtl.DTLVardef@2d0ee2org.highwire.dtl.DTLVardef@2c4bd6org.highwire.dtl.DTLVardef@26db00_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2022

Identifying eukaryotes in drinking water metagenomes and factors influencing their biogeography.

The biogeography of eukaryotes in drinking water systems is poorly understood relative to prokaryotes or viruses. A common challenge with studying complex eukaryotic communities from natural and engineered systems is that the metagenomic analysis workflows are currently not as mature as those that focus on prokaryotes or even viruses. In this study, we benchmarked different strategies to recover eukaryotic sequences and genomes from metagenomic data and applied the best-performing workflow to explore eukaryotic communities present in drinking water distribution systems (DWDSs). We developed an ensemble approach that exploits k-mer and reference-based strategies to improve eukaryotic sequence identification from metagenomes and identified MetaBAT2 as the best performing binning approach for clustering of eukaryotic sequences. Applying this workflow on the DWDSs metagenomes showed that eukaryotic sequences typically constituted a small proportion (i.e., <1%) of the overall metagenomic data. Eukaryotic sequences showed higher relative abundances in surface water-fed and chlorine disinfected systems. Further, the alpha and beta-diversity of eukaryotes were correlated with prokaryotic and viral communities. Finally, a co-occurrence analysis highlighted clusters of eukaryotes whose presence and abundance in DWDSs is affected by disinfection strategies, climate conditions, and source water types. SynopsisAfter benchmarking tools and developing a dedicated consensus workflow for eukaryotic sequence detection in metagenomes, the experimental, environmental, and engineering factors affecting their biogeography in drinking water distribution systems were investigated Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/518372v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1ae8423org.highwire.dtl.DTLVardef@653471org.highwire.dtl.DTLVardef@5606b7org.highwire.dtl.DTLVardef@1d30cde_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2022

The critical role of BTRC in hepatic steatosis as an ATGL E3 ligase

ObjectiveNon-alcoholic fatty liver disease (NAFLD), characterized by hepatic steatosis, is one of the most common causes of liver dysfunction. ATGL is closely related to hepatic steatosis as the speed-limited triacylglycerol lipase. Nevertheless, the expression and regulation of ATGL in NAFLD remain unclear. MethodsUsing immunohistochemistry and qRT-PCR to detect the expression of ATGL and BTRC in different models with hepatic steatosis. Co-IP evaluated the binding of ATGL and BTRC. Knockdown of BTRC employed by adenoviruses and then analyzed the ATGL expression, triglyceride levels, and lipid droplets accumulation. ResultsOur results revealed that ATGL protein level was decreased in animal and cellular models of hepatic steatosis and the liver tissues of cholangioma/hepatic carcinoma patients with hepatic steatosis, while the ATGL mRNA level had hardly changed; which means the decreased ATGL mainly degraded through the proteasome pathway. BTRC was identified as the E3 ligase for ATGL, up-regulated, and negatively correlated with ATGL level. Moreover, adenovirus-mediated knockdown of BTRC ameliorated hepatic steatosis via up-regulating ATGL level. ConclusionsOur study demonstrates a crucial role of elevated BTRC in hepatic steatosis through promoting ATGL proteasomal degradation as a new ATGL E3 ligase and suggests BTRC may serve as a potential therapeutic target for NAFLD. FundingThis study was supported by The National Natural Science Foundation of China (Grants 82070888, 82070882, 82100917, 81872165, 82273116, 82203661, 81901557 and 81902693); Key Project of Nature Science Foundation of Guangdong Province, China (Grant 2019B1515120077); National Key R&D Program of China (Grant 2018YFA0800403); Guangdong Special Support Program for Young Top Scientist (Grant 201629046); Guangdong Natural Science Fund (Grant 2019A1515011810, 2021A1515010434, 2022A1515012423 and 2022A1515012513); Key Sci-Tech Research Project of Guangzhou Municipality (Grants 202201010820) Fundamental Research Funds for the Central Universities (Grant 50000-31620106); China Postdoctoral Science Foundation (Grant 2021M703679, 2020M683110).

cell biology↗

bioRxiv2022

TMEM100, a Lung-Specific Endothelium Gene

The heterogeneity of endothelium across different organs was recently explored using single-cell RNA-sequencing analysis. Compared to other organs, the lung exhibits a distinct structure composed of a thin layer of capillary for efficient gas exchange. In this study, we demonstrate that Tmem100 is a lung-specific endothelium gene.

physiology↗